Imperfection detector



Patented Aug. 1, 1939 UNITED STATES PATENT OFFICE IMPERFECTI ON DETECTOR 6 Claims.

This invention relates to a device for detecting imperfections when printing on rotary textile color printing machines, and the like.

The principal objects of the invention are to provide means whereby there will be evenness of pressure on the doctor blade throughout its length, to secure evenness in the distribution of ink; to provide means for detecting any flaw in the printing caused either by a nick in the doctor blade or by the passage of foreign matter and to, either stop the press thereby automatically or, give a warning signal; to provide an attachment to be placed upon the doctor blade holders in such a printing machine, or any other machine where a doctor blade is used, in which imperfections in the printing caused by the passage of minute particles of the print color which crystallize and get caught between the doctor blade and printing roller, will be detected; to provide means whereby, when such particles get loose and become embedded on the engraved roller, the signal will be given promptly so the machine may be stopped and the continued printing and spoiling of the cloth, or the like be pre- Vented.

Other objects and advantages of the invention will appear hereinafter.

Reference is to be had to the accompanying drawing, in which Fig. 1 is a front elevation of a doctor blade with a preferred embodiment of this invention applied thereto;

Fig. 2 is an end elevation of one of the color printing units of a cylinder rotary textile printing machine, showing the doctor blade and associated parts in section on the line 2-2 of Fig. 1;

Fig. 3 is a detailed view of the connection between the contact bar and contact arm;

Fig. 4 is a diagrammatic wiring diagram, and

Fig. 5 is a sectional view of a precision pin.

As stated, this invention relates to an attachment to be placed on the doctor blade holder of each of the units of a printing machine, as above stated. It will be understood, of course, that the main printing cylinder 10 is adapted for co operation with a series of engraved printing rollers ll, only one of which is shown herein.

Each of these rollers is provided with a doctor blade I2 and the one illustrated here is shown out of position, in order to show the doctor blade in vertical position, in Fig. 2. It is this doctor blade that is apt to show certain defects in the printing of the cloth by the fact that, under certain circumstances, it is relieved from the print roller locally and even nicks taken out of it.

These difiiculties are caused by foreign substances, as for example crystallized ink, lint, dust, and the like, passing under the razor sharp edge of the doctor blade. They cause either of these difiiculties at the blade or, passing around the print roller or on the cylinder, cause trouble in a plurality of print rollers. Any foreign substance that interferes with the normal fiow of the printing color gets picked up by the roller which feeds the print color and may get caught between it and the doctor blade. When that happens, which is a regular occurrence in textile printing, the doctor blade is forced locally away from the print color roller and allows fugitive color to run through and causes imperfections in the finished product. Also the minute particles of ink crystallize and when any one of these gets caught, it raises the doctor blade from the print roller locally. When such particles get loose they pass between the print roller I l and the cylinder it! of the printing machineand become, in many cases, embedded in the engraved print roller I I. As this roller revolves, the foreign particles, which are embedded in it, strike the doctor blade once during each rotation, thereby causing a serious print imperfection. It often happens that these imperfections cut nicks in the edge of the extremely sharp doctor blade, knife, or shear, and, when the blade traverses, two nicks are cut in the doctor blade at times, thereby causing two imperfections in the roll at the same time, instead of one. Also lint and dust often gathers in the print roller.

In these cases the doctor blade moves away from the print roller at some local spot upon it at any point along its edge and causes trouble in the printing at that point until it is discovered. It is not the object of this invention to prevent these occurrences but to warn the operator when the imperfections are taking place or even to stop the macln'ne automatically when they do occur, thus saving a great amount of otherwise discarded cloth.

The parts of the color printing machine so far described are old. The doctor blade I2 is held as usual by doctor blade holders l3 and I4. On the holder I4 are located adjustable holders 15 which extend over the entire surface of the holder I4 and project beyond it. Each holder 15 is provided with slots l6 and bolts [7 by which it can be adjusted for the purpose of moving the parts carried by it toward or from the edge of the doctor blade.

On these holders I5 is located a shaft l8 which extends the Whole length of the doctor blade on adjusted position.

the outside thereof. This shaft is mounted in suitable bearings and it is not used to transmit power but merely as a support for the circular hubs I9 of a continuous series of contact arms 20. These contact arms are parallel with each other and extend to the doctor blade, close to its sharpened edge, and each one has a transverse head 2| thereon. These heads are placed. close together, preferably only about .001 of an inch between each two heads but leaving them free to work independently of each other.

It will be seen that these arms with their heads extend from one end to the other of the doctor blade and that, if any of the above mentioned difficulties occur which would raise the doctor blade, it will be local and will raise some one of these heads more than those next to it. Each contact arm is provided with an electrical contact 22 secured to the contact arm but insulated electrically therefrom.

The hub IQ of each one of these arms is provided with a projection 23 and behind this is a continuous flexible steel wire 24, which is supported in any desired way, but which acts against these projections 23 on the entire line of arms to keep all of the contact arms 20 in a definite position and prevent those located at certain angles from dropping. It will be understood that these contact arms and doctor blades are at a different angle for each print roller and this spring is employed to hold them in the right place. On each side of each hub [9 there is a collar 25 fixed to the shaft 23 to prevent movement of the contact arms along the shaft.

Each of the holders I5 is provided with a precision pin or graduated gauge 26 which is set into the holder near its extreme edge and projects from it slightly. This pin is graduated and is adjustable to secure the proper fine adjustment of the contact bar to and from the doctor blade.

It will be noticed that there are several of these holders along the doctor blade and each one of them is operated in a similar manner. Each of these holders is provided with a slit 21 and a circular slot 28 to receive a screw 29 which screws into a contact bar 30 which extends the length of the doctor blade. Each slit is closed about its screw 29 by a screw 3| in each case so that this bar is held firmly and efiectively in The bar, of course, is provided on the underside with stationary contacts 32 in alignment with the contacts 22 and the pushing of any contact arm. 20 back so that the contact 22 thereon will engage the contact 32 will establish a current through an insulated wire 34 which extends along the holder through the two contacts 22 and 32 to the insulated contact bar 38 and thence through the usual electrical projection to a signal 35, which may be a light, or a bell, or an automatic means for stopping the machine and is not otherwise shown.

It will be noticed that the portion of the adjustable holder 35, which extends toward the edge of the doctor blade, is provided with a contact bar 30, as described, and also with a notch in which the wire 34 is carried and insulated and from which its branches go to the several contacts 22. Also this supports" the shaft 18 in which the contact arms are mounted and is cut out at this end to accommodate these parts and yet it is adjustable as stated.

It will be seen that this attachment involves the adjustable holders l5, each of which acts as a sup-port to a contact arm 20 and for the contact bar and the shaft [8 and the bushings on the shaft. Of course, it will be understood that in use the blade holder is adjusted to such a point that the heads on the contact arms rest against the doctor blade back of this edge and along it. The doctor blades for the several print rollers are placed in the usual position and, as

usual, are adjusted by means, not shown herein,

to perform the important function of regulating the amount of print color that the engraved roller ll carries to the cloth.

The contact bar is set with precision and accuracy by use of the pins 26 which are graduated to a 00% of an inch and inserted in a screwthreaded hole in the contact bar. In this way the contact bar can be set or adjusted Within .00 of an inch from the contact points and the blade has to be raised only that much to warn the operator of an imperfection running through. Furthermore, the blade is rendered perfectly straight and accurate from one end to the other, which also has been difficult heretofore. This results in evenness of pressure of the doctor blade against the print roller and evenness of printing throughout its length.

It is not contended that this instrument is able to prevent all print imperfections or in fact any, but simply gives warning of their presence or other action which may be desired and relates only to those imperfections which arise out of interference with the doctor blade, which are numerous. Also this instrument or its equivalent is not limited to its use on color printing machines where developed colors are used, which is its principal use, but it is intended that the instrument be used on all types of colors or printing inks or any place where a doctor blade is used, whether in the printing industry or otherwise.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is:

1. The combination with a doctor blade and means for supporting it against a print roller or the like, of a series of contact arms engaging said blade, an electrical contact on each arm, a contact bar extending the length of the blade and insulated from the blade and having a series of contacts, one adjacent to each of the first named contacts, said contact arms, each being movable with a slight motion of the edge of the blade, to engage the respective contacts on the contact bar, and electrical connections between the contact bar and each individual contact on the contact arm to complete an electric circuit when any contact is closed to an alarm device, or the like.

2. The combination with a doctor blade and means for supporting it against a print roller or the like, of a series of contact arms on the back of said blade, said arms being located substantially in contact with each other throughout the length of the blade but free from each other so that each arm will operate independently of the others, an electrical contact on each arm, a contact bar extending the length of the blade and insulated from the machine and, having a series of contacts, one adjacent to each of the first named contacts, said contact armsbeing movable by a slight motion of the edge ofthe blade to bring the respective contacts therein into contact with the contacts on the contact bar, and

electrical connections between the contact bar and each individual contact on the contact. arms to conduct a current when the contacts are closed.

3. The combination with a doctor blade, of an adjustable holder connected therewith, a member carried by said holder, a series of radial contact arms loosely mounted on said member, means for holding said contact arms against longitudinal motion, heads on said contact arms which form a substantially continuous line along the doctor blade, each one being free from the next one but extremely close thereto, electric contacts on each contact arm, means whereby, when the edge of the doctor blade is moved, some of the said contacts will complete a circuit and a warning signal in each circuit adapted to be energized by the closing of its circuit to show that the doctor blade is in a position to produce an imperfection in the printing.

4. The combination with a doctor blade, of a holder connected therewith, a shaft carried by said holder and extending along the doctor blade, a series of contact arms movably mounted on said shaft and engaging the blade, each contact arm being free from the next one, electric contacts on each contact arm, means whereby, when the edge of the doctor blade is moved, the said contacts will complete a circuit, and means for providing a warning When any contact is closed to show that the doctor blade is in a position to produce an imperfection in the printing.

5, The combination with a doctor blade, of a series of holders, a shaft carried by the several holders and extending the length of the doctor blade, a series of hubs freely turnable on said shaft, a contact arm carried by each hub, said contact arms engaging the doctor blade just behind its bearing point, a projection on each hub, a steel spring extending the whole length of the doctor blade and engaging all of said projections, thereby holding the heads on the doctor blades in uniform position with relation to the doctor blades, and means carried by said contact arms individually for closing individual circuits and establishing individual currents whenever the adjacent local area of the doctor blade is moved back from ink distributing position.

6. The combination with a doctor blade and means for holding it in position, of a holder carried adjustably by said means, the adjustment being in a direction parallel with the plane of the doctor blade but transverse to its length, a shaft carried by the several holders and extending the length of the doctor blade, a series of contact arms carried by said shaft, a projection on each contact arm, a steel spring extending the whole length of the doctor blade and engaging all of said projections, thereby yieldingly holding the contact arms in uniform position with relation to the doctor blades, and means carried by the said contact arms individually for establishing individual currents whenever a local area of the doctor blade is moved back from ink distributing position.

WILLIAM G. SLATTERY. 

